The use of pallets to contain and transfer cargos, the use of resilient materials to cushion pallet shocks, the use of rollers to support and convey such pallets, and the use of rails to restrain pallets in specified locations are all known in the prior art; see U.S. Pat. Nos. 1,770,614; 2,554,657; 3,612,316; and U.S. Air Force Design Handbook DH 1-11 entitled AIR TRANSPORTABILITY. What is not known in the art and is specifically disclosed herein is a technique and the apparatus for equalizing the loads on a roller type pallet support system when the pallet contains an unevenly distributed load.
The armed forces and other users of palletized cargo transfer systems frequently encounter hardware performance constraints that limit the types of loads they are able to handle. In the case of aircraft, the usual pallet cargo handling system begins with a semirigid pallet upon which the cargo is restrained. The pallets themselves are loaded into aircraft through the cargo door and located within the aircraft by rolling the pallets on a conveyor type system, generally having multiple exposed balls or rollers. Upward movement of the pallet is limited by the rails attached to the aircraft structure, lateral and longitudinal location is maintained with a standard lock system.
Numerous load, weight and distribution constraint must be considered in selecting a load configuration for the total aircraft, one of the most vexing of which is the load limitations of the individual pallet supporting rollers. For example, a heavy vehicle which otherwise does not exceed the aircraft's lift capacity or center of gravity balance often exceeds the specified weight limitations of the rollers immediately below the wheels, as a result of the concentrated load forces being transmitted through the semirigid pallet. Since the roller static weight limitations take into account vibration and acceleration forces encountered during flight, the actual magnitude of static weight allowed per supporting roller is comparatively small. To compensate for this, complex shoring systems made of lumber are used to spread concentrate load over the pallet surface and thereby onto additional rollers.